UHP as a mild and efficient catalyst for the synthesis of substituted imidazoles via multicomponent condensation strategy

Multicomponent reactions (MCRs) allow the assembly of complex molecules in one-pot and show a facile execution, high atom-economy and high selectivity, as afford good yields and are fundamentally different from two-component and stepwise reactions in several aspects. Imidazoles are very useful building blocks for the development of molecules that are important in medicinal chemistry. Substituted imidazole derivatives have found applications as diverse biologic activities such as angiotensin inhibitors, anti-inflammatory, glucagon antagonist, antiviral, antimicrobial, fungicidal and high cytotoxicity, which has indicated them as new candidates in cancer therapy. Because of their importance, the methods for their synthesis have become a focus of synthetic organic chemists. In continuation of our interest in the application of new catalysts in organic synthesis via MCRs, herein, an efficient and  highly  selective synthesis of highly substituted imidazoles has been  developed by the condensation of benzil or benzoin with various substituted aldehydes and ammonium acetate using  urea/hydrogen peroxide (UHP) as a supported green catalyst in refluxing ethanol for 2-5 h under mild reaction conditions and excellent yields.